Rheostat.



R. HEAD.

RHBGSTAT.

APPLICATION FILED 001*. 27, mos.

Patented Dec.28,1909.

2 SHEBTB-BHEET l.

A??? I? M 1: 7 E v. f W

ROBERT HEAD, OF NEW YORK, N.

Y., ASSIGNOB '1'0 ROBERT L. WATKINS, OF NEW YORK. N. Y.

Specification of Letters Patent.

Patented Dec. 28, 1909.

Application filed October 27, 1908. Serial No. 459,719.

To all whom it may concern:

Ilc it known that l, Roman mo, :1 cit-izen of the United States,rcsidin' at New York city. in the county of New h'ork and State of NewYork, have invented a new and useful Improvement in Rheostats, of whichthe following is a specification.

In stereopticons, photomicrographic cameras, motion picture machines andother devices employing clcetricit as a lighting medium. it isfrequently ound necessary to introduce within a circuit a rhcostat orother resistance, which is usually bulky in construction and ofconsiderable weight, therefore being exceedingly awkward to handle intransportation. It is also a fact that 'heostats, as conunonlyconstructed. retain the heatfor quite a long time after the electriccurrent has been cut oil which in many instances is found to be anobjectionable feature. Itis with the view of eliminating theseobjectionable features and roviding certain other improvements whic Iwill be found desirable in a rhcostat used for the pn s above mentioned.

y invention therefore relates to improvements in rheostats, of aportable nature. and the objects of my improvements are: first, toprovide a rheostat that will be light in weight and compact in orm:second. to construct a rhcostat that will remain comparntively coolwhile an electric current passes through it; and third, to present thegreatest. possible area of radiation. thus facilitating the rapidcooling of the rhcostat after the current has been cut oil. I attainthese objects by the mnstruction of a rheostat as illustrated in theaccompanying drawings, in which- Figure 1 is a perspective view of myimproved rhcosl'at in its preferred form. when m use; Fig. :3 is a viewin elevation of the middle section. or frame of some: Fig. 3 is asectional view showing the contacts and the hinge arran cmcnt of theseveral sectious, and is lali cn appmximately on limi-l--3 of Fig. 2.Fig. 4 is n view similar to Fig. 3, in which two of the sections areshown in tluir closed position. which throw them out of the circuit;Fig. 5 is an enlarged dotuil view of some of the contacts. in Figs. 6and 7, l have shown a modification of the contact and hinge nrrangcnu-ntwhich may la' found desirable under certain condilions.

Similar reference characters refer to like parts throughout the severalviews.

In the drawings illustrating one of the forms which my invention maytake, I, 2, 3, 4 and designate the sections of which the rheostat iscomposed; thcscveral sections are similar to the extent that they eachconsist of a metallic frame (3. in which four strips of mica or othersuitable material T, are socured. Upon each pair of the mica strips T,is wound a resistance wire 8 of exceediu ly small gage. the ends ofwhich are elcctrica ly connected with the contact plates 9 and 9 whichare suitably insulated from the frames ti.

In my rhcostat, each section or member comprises a skeleton frame, corecomposed of a plurality of pieces of insulating material, preferablymica, and a resistance wound on each piece of the core. T he core piecesare positioned in the frame so that the side faces-of the pieces are inthe plane of, or parallel to. the corresponding side faces of the frame,said core pieces being arrai'igcd edge to edge. and practically incontact with each other. The resistance coiled on the core pieces arethus positioned in the plane of the frame. the looped parts of eachresistance fitting over the edges of the cure pieces on which it iswound and contacting with the edge of the next core piece, theconvolutions of one coil alternating with the couvolntions of the nextcoils, as shown in Figs. 1. '2 and ti. Said construction andarrangement. of parts are advantageous for a number of reasons: first,the resistance windings are fully exposm'l on the respective sides ofthe. frame to the circulation of air between and a round the memberscomposing the l'licostat sccond. a very compact and economicalconstruction is secured. and. third, the mom her of n'sistance windingsmade possible by the number of core )icces secures an enlurgod radiatingarea in each member of the rhcostat.

liigidly sccurai to the middle section 3. are angle plates l0. 10provided with hearings it in which the trunnions of the scetions 1. 2. 4and ii are jollrunh'd. To the underside of the plate It! is hinged amember I! having wings l2 n'onctmg at right unglus to thc l'uco lhcrool.lho member 1:! servos as a supporting leg. as llUWll in Fig. 1 when therhcuslut is in use. and as a cla p to hold the sections together, whennot in ll i'i llll use. The sections 1 and 5 are also provided with suports 13, adapted to be folded back against t 1e frames (3, as indicatedby dotted lines in Fig. 1.

The contact vidcd with a ownward pro'ectmg tongue or ndant t) formin oneo the terminals of the rheostat to \vhic may be attached one of thewires 14, of an electric circuit. The contact plate 9, of section 1 isalso provided with a endant similar to 9, to which may be attac ed thewire 15, Fig. 3, to complete the electric circuit.

As shown in the drawings, the wires 14 and 15 terminate in slotted plugs14: and 15' and connection is established with the rheostat by forcingthe ndants 9'-' of the contact plates 9 and 9, o the sections 1 and 5respectively, into the slots of the tplugs 14 and 15 It is obvioushowever at many other methods of connecting the wires 14 and 15 to therhcostat may be employed within the scope of my invention.

In Fi 5, which is snbstantiall an enlarged view of Fi 4, with two thesections eliminated, have shown in diagrammatic form the electriccircuit and the manner in which the resistance of the middle section iscut out.

If the full resistance of the rheostat is desired, all the sections areopened, as shown in Figs. 1 and 3, in which sition the electric currentwill be for to traverse the resistance wires of all the sections. becurrent may enter the rheostat through either of the terminals, but forthe purpose of illustration we will assume it enters through the contactplate of section 1 and pames along the resistance wire 8 thereof to thecontact plate 9 of section 1, thence to contact plate 9 of section 2,along its resistance wire 8 to the contact plate 9 thereof and so onthroughout the several sections of the rheostat leaving some by thecontact late 9 of the last section 5. If however it IS desirable to cutout the resistance of one or more of the sections, they may be returnedto their closed position, as shown in Fi s. 4 and 5.

n Fig. 4, the resistance of sections 2 and 3 is shown as cut out of thecircuit, but for the purpose of better illustrating the method thereof,reference may be made to Fig. 5 wherein the resistance of the middlesection is in like manner cut out of the circuit.

It will be seen by referring to Fig. 5 that the current will enter therheostnt b the contact plate 9 of the first. section an pass through theI'CnlStlllNB 8 thereof, to the contact late H of same, as previouslystated; hut in the :resout. instance the current is shunted to tiecontact plate 9 of the next section, via the rivet 6 and contact. 17,thus avoiding the insist-name of that mrtlculnr section. The contactplale E) of tie motion late 9 of section 5 is pro just referred to andthe plate 9 of the next section 5, being in contact with each other, theelectric current will continue along the resistance 8 of section 5 andto the terminal thereof. It is evident therefore that the differentdegrees of resistance offered by a. rheostat as ascribed, will beproportionate to the number of sections contained in the rheostat; it.is also evident that at least one of the sections will always beincluded in the circuit.

For purposes requiring a uniform resistance, I prefer to construct therheostat as shown in Figs. 6 and 7 wherein the 6 frames of each of thesections 1, 2, 3, 4 and 3 are pro vided, respectively, with twoinsulated members 20 and 20 21 and 21, 22 and 22. 23 and 23,- 24 and 24which in addition to forming terminals for the resistance wires of theseveral sections, also serve as hinge cr swivel joint, connecting thesections both mechanically and electrically to the post 25. The post 25is made in two parts insulated from each other at 26. In the end of theu per part of the post 26, and in the side 0 the lower part, I providesockets 27 and 28 to reeeive t e plugs 14 and which form the terminalsof the wires 14 and 15. In a rheostat of the above descri tion. theelectric current passes through tie resistance wires 8 of all thesections at the same time, entering via the terminals 20, 21 22, 23 and24 from the upper part of the post 25, and leaving the several sect ionsvia the terminals 21, 22 23, and 24 to the lower section of the post 25,or vice versa.

As a convenient means of elevating the rheostat slightly above thesurface upon which it. may be resting. I extend the front stile of theframes 6 of sections 1 and F- sli htly beyond the lower edge of theframes, an in like manner the lower part of the post is extended, thusproviding three legs or supports, 6 and 25.

As shown in Fi 6 insulating pads 29 and 30 are secured to t hc ends ofthe legs 6 and 25 In a rheostat of the construction shown in Figs. 6 and7, the resistance will be constant regardless of the relative positionof the several sections. therefore the only ap parent object in hingingthe sections together. is that of compactness, which is the chief objectsought in the resent. invention. and may be attained by to ding thesections together, lmokwiso. when the rhcostnt is not in use.

\Vhile l have shown but two of the forms. my invention may take. I donot care to be limited thereto, as it is obvious that severalmodifications may be made without departing from the spirit of myinvention.

am aware t mtrhrostnts of u more or loss bulky form, which usuallyhrcmuc a permuuout. fixture when intrmlured into an electric circuit arein general use, l am also aware that rheostats of both constant andvariable resistances are in use. but I am not aware that heretofore anysuch improvements have been made in rheostats. as are emlmdicd in myresent invention. nor for the purposes herein set forth.

'Iherefore what I claim as new and desire to secure by Letters Patentis:

I. In a rbeostat, a plurality of frames. suitable supporting stripscarried wit-hm said frames, resistance coils mounted apan the supportingstrips and means operat b the relative movement of said frames forcontrolling the flow of current through said resistance coils.

2. In a rheostat, a plurality of frames carrying supporting strips,suitable resistance material mounted upon said supports, means foryieldingly connecting the frames, and means operated by the movement ofthe frames relative to each other for electrically connecting theresistance material of the several frames in series.

3. In a rheostat, the combination of a plurality of sup )orting frames,a hinge member connecting the several frames,- supporting memberssecured within said frames, resistance. material mounted upon thesupporting members, insulated contact plates forming terminals for theseveral sections of resistance; the contact plates of the various framesadapted to be thrown in or out of electrical contact with the plates ofthe frames adjacent thereto, substantially as shown.

4. In a rheostat, the combination of a plurality of supporting frames, ahinge eonneeting the several frames, supporting members secured withinsaid frames, resistance material mounted upon the supporting mem bers,insulated contact. plates forming terminals for the several sections ofresistance: the contact. plates of the various frames adapted to bethrown in or out of electrical contact with the plates of the framesadjacent thereto. and supporting members or elevating the rhcostat,adapted to be folded laterally against. the frames substantially asshown and set forth.

5. lo a rhcostat. a plurality of sections consisting of a suitableresistance material mounted upon supporting strips, said strips securedwithin a frame. a pillar or support consisting of two insulatingsections, means for yieldingly connecting the sections to the pillar,and means for establishing electrical connection between the resistancematerial and the pillar substantially as shown and described.

(1. In a rheoslat. a member comprising an open frame. a core composed ofa plurality of pieces of insulating; material. said core beingpositioned within the frame. and the pieces composing the euro beingassembled edge to edge with reference to each other, and a plurality ofresistances wound individually on the core pieces, said l'wislanccslying substantially in the planes of the respective faces of 1 10 frame.

7. In a rheostat, a member comprising an open frame, a plurality of corepieces positioned within said frame, said core pieces being assemblededge to edge with respect to each other and lying substantially in theplanes of the respective faces of the frame. and a )lurality ofresistance windings coiled individually on the core pieces.

8. In a rhcostat, a member comprising an open frame, a plurality of micacores positioned within said frame. said mica cores being assembled inedge to edge order, and substantially in contact. along their edges. anda plurality of resistances wound individually on said cores.

9. In a rheostut, a member comprising an open frame, a lurality of flatcore pieces socured in said nune and positioned edge to edge withrespect to each other, and resistance coils wound on said core pieces,the windings of one resistance coil alternating with the convolutions ofthe next adjacent coil.

10. In a rhcostat, a member comprising, a core composed of a sheet ofmica divided to produce a series of lengths, said lengths bemg disposedin edgewise opposing relation, and a resistance com iosed of a. metallicwinding supported by t as mica sheet.

11. In a rheostat, a plurality of members flexibly connected foradjustment relative to each other, whereby said members may be spacedfor the circulation of air between them, each member having a resistanceexposed to the air, and means operated by the adjustment of said membersfor regulating the flow of current through the resistances.

12. In a rheostat, a plurality of resistance members llexiblv connectedfor adjustment into compact relationship and adapted to be separatet forthe circulation of air between and around said members, and meansdcendcnt upon the movement of said memms for controlling the flow ofcurrent into the resistances thereof.

[3. In a rheostut. a plurality of resistance ca rrying membersadjustable into compact relationship and adapted to be relativelyseparated. and means dependent upon the positions of the members forcontrolling the flow of current through the resistances.

14. In a rheostul, a plurality of resistance carrying members adjustableinto compact relationship and into spaced order, and means controllableby the adjustment of said members for cutting them into and out of anelectric circuit.

15. In a rheostat, a plurality of adjustable resistance carryingmcuda-rs. and means coutrollahlc by the adjnsluu-nt of said members forcutting them into and out of an clorlrio circuit.

16. In a rheostab, a plurality of movable carrying members each havin onresistance, and means contro able by the movement of said members forcutting the resistances into or out of an electric circuit.

17. In a rhcostat, a plurality of movable resistance members, means forsup orting the same, and means controllable y the movement of saidmembers for including them into an electric circuit.

18. In a rheostat, a plurality of movable resistance members eaciadapted to be exsed for the free circulation of air in contacttherewith, and means 0 rated by the movement of. said members or cuttingthe resistances into and out of an electric circuit.

19. In a rheostat, a plurality of resistance members movable withrespect to each other,

members hinfiedly connecte whereby said members may be separatedlaterall and means operated by the movement 0 said members for cuttingthem into or out of an electric circuit.

20. In a rheostat, a pluralit of resistance for lateral movement WIT,respect to each other, and swatch devices operated by the movement ofsaid members for cutting them into or out of an electric circuit.

In witness whereof I have hereunto set my hand this 24th do of October1908 in the presence of two su ribing witnesses.

ROBERT HEAD lVitnesses J. M. Mammm'r, Ronmrr L. Wxrxms.

